Do I need an owl guard for 6X6X12 compartments ?

[Dave Duit]

I have a naturehouse DR-12N; a 12 compartment martin house that I coverted to 6 compartment. The compartment size is 6X6X12. With the added depth of the compartments is in necessary to have an owl guard or will the depth be enough protection ? I have owls around my location.

[Emil Pampell-Tx]

Dave, I have often wondered about the same thing. The question is whether the martins move to the back of the compartment when an owl sits at the entrance (if they do, then the 12in compartment is deep enough). I also have a lot of owls.

Another idea that I have is that if you use an SREH entrance and the entrances is within 1/4in of the porch, then an owl just simply cannot squat low enough to put their foot into the compartmnet more than probably 2 or 3 inches. I have large porches, 3in x 6in, so the porch helps this situation as the owl cannot hang onto the entrance because the porch is in the way.

Another idea that I think helps with owls is to put up a baffle of some sort so the owls cannot see the martins. I have noticed with all of my offset tunnels that the martins build their nests so they cannot be seen from the entrance. If the owls cannot see the martins, then I doubt that they will be trying to grab them. Some people use a baffle so the martins must go around it to get to the back of the compartment. Why would an owl try to reach into a hole if it cannot see anything in it? Because of this idea I am using tunnels in my gourds and putting the offset tunnels pointing to one side so the owls cannot see the martins. With the tunnels, the owls simply cannot reach into the gourd part of the cavity.

In summation, if an owl cannot see anything and if it cannot reach very far thru the SREH, then I think the martins are safe, and the owls surely will come take a look, but give up and leave after a bit.

Now if an owl starts catching martins, they will keep coming back and they get a lot smarter. I had an owl one year that flew into the gourds, flapped its wings, and tried to scare out the martins. It played volleyball with my gourds. I had about 90 martins here, and these martins were so afraid that they left at night, and came back the next day.

[Steve Kroenke]

Dave,

Owls locate martin colonies by two methods: sound and sight. It is usually the nocturnal vocalizations and other sounds made by martins inside their nests that initially attract owls. So any kind of housing, including deep compartments with srehs, round entrances or tunnels, will not prevent this. Once the owl reaches the colony site, he continues to listen and look. Vertically/horizontally deep cavities provide protection as long as the martins stay away from the entrances, but they don?t stop martins from sitting in or near the entrances early in the mornings. Male martins, in particular, will dawn sing near the entrances to their nests. If you have porches, then this may encourage martins to come closer to the entrances and even come out. When martins sit in the entrances, both srehs and round, or sit on porches, then owls will swoop to them and try to grab the martins. With srehs, the martins have a harder time exiting and fleeing. But srehs do help keep big owls from reaching inside.

I have seen what barred owls can do to martins in T-14 houses with srehs, deep compartments and even wire baffles. Again the martins will sit near the entrance holes in the early mornings and the owl tries to grab the martins. Owls decimated large numbers of martins in a super colony that used srehs, including leaving dead martins lodged in these entrances. Owls may also break off or dislodge both plastic and metal porches on super gourds when they swoop to grab visible martins near the srehs. The power of a large barred or great horned owl is awesome.

I would encourage you to place some kind of external baffles on your housing to prevent owls from hovering in front of the compartments or seeing the entrances. You can use the wire cage method but that does not prevent owls from seeing the entrances; but these guards are better than none at all. One approach I have used many years ago is to place external baffle plates in front of the entrances which blocks off visibility from the outside. I attached these to porches and the martins could easily go around the baffle from the side of the open porch and enter the entrance. I was using hexagonal houses and I simply placed about 4 or 5 inch wide aluminum strips to the front of each porch on the outside. This blocked off visibility and the martins could easily land on the porch on either side of the baffle, turn, and enter the entrance. I believe some folks on the Forum, including R. C. Moser have recently used this method.

Again, the horizontally deep compartments will NOT prevent martins from being visible when sitting near the entrances. And owls have no difficulties seeing martins that are near the entrance holes, including srehs and round. I have Lone Star houses with 6? x 12? compartments and I have watched martins sit near the entrances early in the mornings prior to the males leaving to dawn sing. This is suicide when owls are actively predating a martin colony. Owls could have easily swooped in and tried to grab these vulnerable martins. The deep cavities will NOT stop an owl from predating visible martins that are near the entrances, including srehs and round.

Good luck.

Steve

[Emil Pampell-Tx]

Steve, in other words, nothing prevents a martin from being caught if they sit at the entrance or on the porch, I agree with that. I have however not had any problem with the entrances or porches being dislodged by owls. It probably depends upon how agressive each owl is, and how strong the porches & entrances are. The owls that tear up porches & entrances have probably caught a lot of martins at that location, so I still think porches help, and I certainly will continue to use them. I love those porches, and so do the martins. The secret in my opinion is to try to keep the owls from catching their first martins, but that may be an impossible task. I also think that a martin will flush quicker if it can see an owl hanging onto the entrance hole or looking into the entrance. I don't think that we will ever completely stop the owls, they are too persistant.

[Steve Kroenke]

Emil,

Yes, if your porches are well attached to the gourd front, then most owls would not be able to dislodge them. I saw the metal perches that are used on super gourds pulled up or down when the owls would strike upon seeing martins near the srehs. The porches do greatly help martins to enter srehs and martins will definitely sit on them. I use wire perches on my gourds with the PVC tunnels attached to the necks and the martins seem to enjoy sitting on them. But owls are extremely powerful. I have seen Trio flip up doors ripped off and carried away by barred owls. I have seen natural gourd fronts around the entrances broken apart and the owl?s talons penetrated the gourd. This year great horned owls hit Bob?s T-14 perches that fledglings roosted on and the power of the owl broke the perch from cedar porches. The wood was actually cracked some on the porch.

It is the male martins and non-incubating/non-brooding females which are most vulnerable to flushing when an owl tries to raid a gourd or house. These martins are more skittish. A female martin with eggs or young will usually sit tight on her nest and not panic as easily. The sight of a huge owl hovering around a gourd or house most surely creates total terror for any martin sitting near the entrance!

I completely agree with you about stopping owls from catching their first martin. Once they succeed, they keep coming back. Accipiter hawks are the same. This relates to the Optimal Foraging Theory concept where a predator will continue to feed in an area where prey is easy to catch and the predator is nearly always successful.

Every morning, I get up and maintain a presence around my colony from about 4:00 am to dawn. It is during this time that male martins are most vocal. My animated presence around the colony keeps both barred and great horned owls from visiting.

The only method that has worked the best for me so far has been my sound deterrence system which masks the nocturnal vocalizations of the martins; this involves playing loud music at night. As long as the owls never recognize a colony as a source of food, then they have no reason to visit. But this system may not work when martin fledglings roost in the open on gourd crossbars or house perches/porches. However, playing loud music at night is not practical for most folks!

I agree that we will probably never completely eliminate owl predation. I mainly want to greatly minimize the chances that adult martins will be predated. There is little one can do legally to stop owls from catching the martin fledglings that roost in the open.

Steve

[Dave Duit]

Both suggestions are very valuable. This has given me new insight into owl attack behavior.